The present invention relates to an antenna device, which is, for example, installed in an internal space in a vehicle door handle, and can be used in a communication system with which doors are locked and unlocked by remote control, or the like.
In recent years, automobiles are often equipped with keyless entry systems, which lock and unlock doors without key operations. In keyless entry systems, the doors of a vehicle are locked and unlocked by remote control over short distances with an LF band (low frequencies of 30 to 300 kHz) communication system, in which an antenna device is installed in a door handle on the outside of the vehicle in order to communicate with a portable device, which is carried by the user of the vehicle.
For example, Japanese Patent Laid-Open Publication No. 2016-52035 discloses an antenna device in which an antenna is arranged in a tubular case. In this antenna device, a coil is wound around a magnetic-material core that is fixed in a holder, the two ends of the coil are connected to one of the ends of two metal terminals that are fixed on the holder, and two lead wires, which are connected to the other of the ends of the metal terminals, are lead out to the exterior of the case.
With the antenna device described in Japanese Patent Laid-Open Publication No. 2016-52035, even if the lead wires were to be pulled, the tensile force would be prevented from acting directly on the coil, such that disconnection of the coil can be prevented, and thus the durability and reliability were excellent.
However, in the antenna device described in Japanese Patent Laid-Open Publication No. 2016-52035, the two ends of the coil and the two lead wires must each be electrically connected to the two metal terminals, such that there are problems in terms of increased material costs and manufacturing costs.